Direct synthesis of metal-containing CHA zeolites

ABSTRACT

A metal-containing chabazite zeolite, which has an FTIR peak area ratio between the peak at 900-1300 cm −1  (Si—O—Si asymmetric stretch) and the peak at 765-845 cm −1  (˜805 cm −1  is Si—O—Si symmetric stretch) of at least 55. A method for preparing metal-containing CHA zeolites with high SCR activity at low reaction temperatures from alkali cation-free reaction mixtures that contain the three OSDA structures: metal-polyamine, N,N,N-trimethyl-1-adamantyl ammonium (TMAda+) and TMAOH. The metal-containing CHA zeolites produced by the disclosed method can be identified by XRD, FTIR spectroscopy, FT-VIS spectroscopy, and scanning electron microscopy. A method of selective catalytic reduction of NOx in exhaust gas using the material described herein is also disclosed.

TECHNICAL FIELD

The present disclosure relates generally to a direct synthesis method ofproducing metal-containing chabazite (CHA) zeolites, metal-containingchabazite (CHA) zeolites made using the disclosed methods, and methodsof selective catalytic reduction using the disclosed zeolites.

BACKGROUND

Metal-containing aluminosilicate CHA-type zeolites, such as Cucontaining CHA zeolites, are important catalysts used in commercialselective catalytic reduction (SCR) systems for NOx abatement inautomotive applications. Due to the stringent emission regulations,commercial Cu containing CHA zeolites are required to display high SCRactivity especially at low exhaust temperatures.

Commercial Cu containing CHA catalysts are typically produced from thefollowing steps. First, CHA-type zeolites are produced from reactionmixtures that contain alkali cations. Second, the alkali containingzeolites are ion-exchanged (e.g. ammonium exchange) to remove the alkalications from the zeolite. Third, the ammonium containing zeolites areexchanged with Cu ions to obtain the Cu containing zeolites. However,the additional ammonium and Cu exchange steps to achieve Cu containingCHA caused increased synthesis cost and lowered efficiency. As a result,there is a need for direct synthesis methods for synthesizing highlyactive Cu containing CHA zeolites that do not require ammonium exchangeand Cu exchange.

Prior to this invention, other reported direct synthesis methods for Cucontaining CHA zeolites produce catalysts with a variety of problems.For example, the catalysts typically did not exhibit high SCR activitycharacteristics that are required for commercial applications or hadlimitations to the processing techniques. For example, such synthesismethods often require large amounts of expensive organicstructure-directing agents (OSDAs) that increase costs or require theuse of alkali in the synthesis which need extra ion exchange steps toremove.

The direct synthesis method of making a Cu containing microporouscrystalline material is directed to overcoming one or more of theproblems set forth above and/or other problems of the prior art.

SUMMARY

In one aspect, the present disclosure is directed to a metal-containingchabazite zeolite, which has an FTIR peak area ratio between the peak at900-1300 cm⁻¹ and the peak at 765-845 cm⁻¹ of at least 55.

In another aspect, the present disclosure is directed to a method ofselective catalytic reduction (SCR) of NOx in exhaust gas. The methodcomprises contacting exhaust gas, such as in the presence of ammonia orurea, with a zeolitic material comprising a copper containing CHA-typezeolite, which has an FTIR peak area ratio between the peak at 900-1300cm⁻¹ and the peak at 765-845 cm⁻¹ of at least 55.

Another aspect disclosed herein is a direct synthesis method of making aCu containing microporous crystalline material from reaction mixturesthat (1) are essentially void of alkali metal cations and (2) containCu-polyamine complex (e.g. Cu-TEPA) as the first OSDA and Copper sourceand (3) contain N,N,N-trimethyl-1-adamantyl ammonium (TMAda+) ortrimethylbenzylammonium (TMBA+) or N,N,N-dimethylethylcyclohexylammonium (DMECHA+) organic as the second OSDA and (4) containtetramethyl ammonium (TMA+) or tetraethyl ammonium (TEA+) organic as thethird OSDA.

In an embodiment, there is described a method of making a microporouscrystalline material from reaction mixtures that are essentially void ofalkali metal cations, and that comprise organic structure directingagents (OSDA) selected from (1) metal-polyamine as the first OSDA, (2)N,N,N-trimethyl-1-adamantyl ammonium (TMAda+), ortrimethylbenzylammonium (TMBA+) or N,N,N-dimethylethylcyclohexylammonium(DMECHA+) organic or mixtures thereof as the second OSDA, and (3) TMA+or TEA+ or mixtures thereof as the third OSDA. In this embodiment, themethod comprises: a) mixing sources of alumina, silica, water, a firstOSDA, a second OSDA and optionally a third OSDA and optionally a seedmaterial to form a gel; b) heating the gel in a vessel at a temperatureranging from 80° C. to 250° C. to form a crystalline chabazite product;and c) calcining the product to produce an aluminosilicate zeolitehaving a CHA structure, and a silica-to-alumina ratio (SAR) ranging from5 to 60.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures are incorporated in and constitute a part ofthis specification.

FIG. 1A is an x-ray diffraction pattern and FIG. 1B is a deconvolutionof peaks between 30-32° for a sample made in accordance to Example 1.

FIG. 2A is an x-ray diffraction pattern and FIG. 2B is a deconvolutionof peaks between 30-32° for a sample made in accordance to Example 2.

FIG. 3A is an x-ray diffraction pattern and FIG. 3B is a deconvolutionof peaks between 30-32° for a sample made in accordance to Example 3.

FIG. 3C is an x-ray diffraction pattern and FIG. 3D is a deconvolutionof peaks between 30-32° for a sample made in accordance to Example 4

FIG. 4A is an x-ray diffraction pattern and FIG. 4B is a deconvolutionof peaks between 30-32° for a sample made in accordance to ComparativeExample 1.

FIG. 5A is an x-ray diffraction pattern and FIG. 5B is a deconvolutionof peaks between 30-32° for a sample made in accordance to ComparativeExample 2.

FIG. 6A is an x-ray diffraction pattern and FIG. 6B is a deconvolutionof peaks between 30-32° for a sample made in accordance to ComparativeExample 3.

FIG. 7A and FIG. 7B are scanning electron microscope (SEM) images atvarious magnifications of Example 1.

FIG. 8A and FIG. 8B are scanning electron microscope (SEM) images atvarious magnifications of Example 2.

FIG. 9A and FIG. 9B are scanning electron microscope (SEM) images atvarious magnifications of Example 3.

FIG. 9C and FIG. 9D are scanning electron microscope (SEM) images atvarious magnifications of Example 4.

FIG. 10A and FIG. 10B are scanning electron microscope (SEM) images atvarious magnifications of Comparative Example 1.

FIG. 11A and FIG. 11B are scanning electron microscope (SEM) images atvarious magnifications of Comparative Example 2.

FIG. 12A and FIG. 12B are scanning electron microscope (SEM) images atvarious magnifications of Comparative Example 3.

FIG. 13A shows Fourier-transform infrared spectroscopy (FTIR)/AttenuatedTotal Reflection (ATR) spectra of calcined Examples 1-4 and ComparativeExamples 1-3.

FIG. 13B shows the same spectra normalized based on Si—O—Si symmetricstretch from 765 to 845 cm⁻¹.

FIG. 14 shows Fourier-transform visible spectrum (FT-VIS) of calcinedExamples 1-4 and Comparative Examples 1-3 normalized based on 1 wt. %CuO content with a Cu(OH)₂ powder as a reference.

Aside from the subject matter discussed above, the present disclosureincludes a number of other features such as those explained hereinafter.Both the foregoing description and the following description areexemplary only.

DETAILED DESCRIPTION OF THE INVENTION

As used herein “essentially void of alkali metal cations,” means havingtrace amounts of alkali metal cations. In an embodiment, “essentiallyvoid” or “trace amounts” means 0.3 wt % alkali oxides, such as Na₂O orK₂O, or less.

As indicated, the disclosed zeolite comprises a metal-containingchabazite zeolite, such as a copper or iron containing zeolite, whichhas an FTIR peak area ratio between the peak at 900-1300 cm⁻¹ and thepeak at 765-845 cm⁻¹ of at least 55. In an embodiment, the chabazitezeolite has a silica-to-alumina ratio (SAR) ranging from 5 to 60, suchas from 10 to 50, or even from 10 to 30.

When the described zeolite comprises copper, it is present in an amountof at least 0.5 weight percent of the total weight of the material, suchas an amount ranging from 0.5 to 10 weight percent of the total weightof the material.

When the described zeolite comprises iron, it is present in an amount ofat least 0.5 weight percent of the total weight of the material, such asan amount ranging from 0.5 to 10 weight percent of the total weight ofthe material.

In an embodiment, the total alkali oxide amount is present in an amountless than 0.3 weight percent, such as less than 0.1 weight percent.

In an embodiment, the disclosed zeolite has a peak area ratio betweenthe FT-VIS peak ranging from 500-1100 nm and the FT-VIS peak of Cu(OH)₂between 500-1100 nm of lower than 2.5.

The disclosed method of making a microporous crystalline material andthe resulting Cu containing zeolite material having a CHA-type frameworkstructure are directed to overcoming one or more of the problems setforth above and/or other problems of the prior art. Unlike the priorart, for example, there is described a method for preparing Cucontaining CHA zeolites with high selective catalytic reduction (“SCR”)activity at low reaction temperatures from alkali cation-free reactionmixtures that contain the following OSDA structures: Cu-polyaminecomplex (e.g. Cu-TEPA) as the first OSDA and Cu source;N,N,N-trimethyl-1-adamantyl ammonium (TMAda+) or trimethylbenzylammonium(TMBA+) or N,N,N-dimethylethylcyclohexylammonium (DMECHA+) organic asthe second OSDA; tetramethyl ammonium hydroxide (TMAOH) or tetraethylammonium hydroxide (TEAOH) as an optional third OSDA.

Cu-polyamine complex serves as both the OSDA and Cu source. In oneembodiment, polyamine may be selected from Diethylenetriamine,triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine,N-(2-hydroxyethyl) ethylenediamine,N,N-bis(2-aminoethyl)-1,3-propanediamine, 1,2-bis(3-aminopropylamino),1,4,8,11-tetraazacyclotetradecane,1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, and combinationsthereof, amongst others. In an embodiment, the polyamine istetraethylenepentamine.

In an embodiment, the method of making a microporous crystallinematerial from reaction mixtures that (1) are essentially void of alkalimetal cations and (2) contain Cu-TEPA as the first OSDA and (3)N,N,N-trimethyl-1-adamantyl ammonium (TMAda+) as the second OSDA and (4)TMA+ or TEA+ as the third OSDA.

In an embodiment, the method comprises:

a) mixing sources of alumina, silica, water, Cu-TEPA, TMAdaOH, TMAOH (orTEAOH) and optionally a seed material to form a gel;

b) heating the gel in a vessel at a temperature ranging from 80° C. to250° C. to form a crystalline chabazite product; and

c) calcining the product to produce an aluminosilicate zeolite having aCHA structure, and a silica-to-alumina ratio (SAR) ranging from 5 to 60,such as from 10 to 50, or even from 10 to 30.

In an embodiment, the gel may have a water to silica (H₂O/SiO₂) molarratio of 1-50. The gel may also have a TMAdaOH to silica (TMAdaOH/SiO₂)molar ratio ranging from 0.01-0.5. In one embodiment, the as synthesizedmaterial following step b) exhibits an XRD peak area ratio between the[3,1,0] peak and the peak doublet (sum of [3,−1,−1] peak and [3,1,0]peak) of at least 0.15.

In one embodiment, the reaction mixtures with (A) molar composition 1SiO₂:m Al₂O₃:n Cu-TEPA:x TMAdaOH:y TMAOH:z H₂O, where m=0.016-0.2,n=0.01-0.12, x=0.01-0.50, y=0.01-0.50, z=1-50 and (B) traceconcentrations of alkali cations.

In one embodiment, the disclosed method may further comprise adding tothe microporous crystalline material at least one metal chosen fromcopper, iron or combinations thereof, to form a metal containingchabazite.

When the metal added to the microporous crystalline material comprisescopper, the copper comprises at least 0.5 weight percent of the totalweight of the material, such as an amount ranging from 0.5 to 10 weightpercent of the total weight of the material.

When the metal added to the microporous crystalline material comprisesiron, the iron comprises at least 0.5 weight percent of the total weightof the material, such as an amount ranging from 0.5 to 10 weight percentof the total weight of the material.

Non-limiting examples of sources of alumina that may be used in thepresent disclosure include aluminum hydroxide, such as aluminumtrihydroxide, alumina, alumina hydrates, aluminum alkoxides, aluminumnitrate, aluminum sulfate and aluminum acetate.

Non-limiting examples of sources of silica that may be used in thepresent disclosure include colloidal silica, silica gel, precipitatedsilica, silica-alumina, fumed silica, silicon alkoxides, and the like.

Non-limiting examples of sources of copper that may be used in thepresent disclosure include copper salts such as cupric acetate, cupricnitrate, cupric sulfate, cupric hydroxide, cupric oxide and cupricchloride.

Non-limiting sources of iron that may be used in the present disclosureinclude an iron salt such as ferric nitrate, ferric chloride, ferrouschloride, and ferrous sulfate.

The suitable metals used for forming metal-polyamine complexes are notlimited to Cu and Fe, which are usually used for SCR applications.Optionally the transition metal centers can also be Mn, Co, Ni, Pd, Ptand Zn.

The molar polyamine/metal ratio that may be used in the presentdisclosure is 0.2-5, such as 1-2.

In one embodiment, there is disclosed a copper containing chabazitezeolite synthesized according to methods described herein. In oneembodiment, the disclosed copper containing chabazite zeolite in theas-synthesized form exhibits an XRD peak area ratio between thehigher-degree [3,1,0] shoulder peak of the XRD peak doublet at 30-32° 2theta and the whole peak doublet ([3,1,0] and main [3,−1,−1] peak) is atleast 0.15.

In an embodiment, the disclosed Cu containing zeolite material has anabsorbance of the FTIR peak centered at 1030-1080 cm⁻¹ of at least 0.3absorbance units. In an embodiment, the disclosed Cu containing zeolitematerial having a CHA-type framework structure, has an intense peak near1050-1070 cm⁻¹ FTIR spectrum, which is much weaker in the products fromthe prior art. In an embodiment, the peak area ratio of the peak at900-1300 cm⁻¹ to the peak at 765-845 cm⁻¹ (805 cm⁻¹ is Si—O—Si symmetricstretch) is at least 55 for the disclosed zeolite material, such as atleast 60.

In an embodiment, the disclosed Cu containing zeolite material having aCHA-type framework structure, has a peak area in the 500-1100 nm rangeof the FT-VIS spectrum much lower than that in the products from theprior art. In an embodiment, the ratio of the peak area of Inventiveexamples relative to the reference Cu(OH)₂ peak area is below 2.5, suchas below 2.2.

The Cu containing CHA zeolites produced by the disclosed method can beuniquely identified by methods that characterize detailed structure andmorphology of zeolites. The inventors have shown that X-ray diffraction(XRD), FTIR spectroscopy, FT-VIS spectroscopy, and scanning electronmicroscopy (SEM) can be used to easily differentiate the Cu CHA zeolitesprepared from these disclosed methods from CHA zeolites produced fromprior synthetic methods.

In an embodiment, there is disclosed a Cu containing zeolite materialhaving a CHA-type framework structure, having a crystal morphology,including crystal size, which is different from the products from priorart. The zeolite crystals prepared using the disclosed methods have asize ranging from 0.1-10 microns. In an embodiment, each crystalcontains nanocrystals. The crystal surfaces of the comparative samples 1and 3 are smooth with some nanoparticles partially deposited on theirsurfaces. The crystals of comparative sample 2 are very large (about 5microns) and contain many layers of small crystals.

In an embodiment, there is disclosed a method of selective catalyticreduction (SCR) of NOx in exhaust gas using the material describedherein. For example, in an embodiment, the method comprises contactingexhaust gas with a zeolitic material comprising a copper containingCHA-type zeolites, which show higher SCR activities at low reactiontemperatures (150° C., 175° C., 200° C.) than the products from priorart.

In another embodiment, the method comprises contacting exhaust gas witha zeolitic material comprising a copper containing CHA-type zeolites,which show higher SCR activities at low reaction temperatures (150° C.,175° C., 200° C.) than the products from prior art upon the hydrothermaltreatment at 750° C. with 10% moisture for 16 hrs.

In an embodiment, the contacting step for the method of selectivecatalytic reduction (SCR) of NOx in exhaust gas is performed in thepresence of ammonia or urea.

EXAMPLES

The following non-limiting examples, which are intended to be exemplary,further clarify the present disclosure.

Example 1—Direct Synthesis of Cu-CHA

Pseudo-boehmite alumina was dissolved into a mixture of Cu-TEPA,TMAdaOH, and TMAOH solution for about 60 minutes followed by slowaddition of silica sol (40% SiO₂, Ludox AS-40). The gel was stirred for60 minutes and seed material was added (1 wt. % of total mass ofsilica+alumina) before loading into an autoclave (Parr Instruments). Themolar composition of the gel was 1.0 SiO₂/0.042 Al₂O₃/0.028Cu-TEPA/0.062 TMAdaOH/0.062 TMAOH/12.5 H₂O.

The autoclave was heated to 160° C. and maintained at the temperaturefor 96 hours while stirring at 150 RPM. After cooling, the product wasrecovered by filtration, washed with deionized water, and dried in a110° C. convection oven. The as-synthesized product was examined by XRD,and it was found a Cu containing zeolite having chabazite framework hadbeen obtained (FIG. 1). The product was calcined in air at 600° C. for 5hrs to remove the residual organic. The occluded organic in the driedas-synthesized zeolite was removed by calcination in air at 600° C. for5 hours. The product had a SiO₂/Al₂O₃ ratio (SAR) of 22.2 and contained3.7 wt. % CuO (Table 1).

Example 2—Direct Synthesis of Cu-CHA

Sample 2 was prepared using the same protocol as described in Example 1except the molar composition of the final mixture was adjusted toprepare a CHA zeolite with a different SAR. The composition of the finalreaction mixture was 1.0 SiO₂/0.049 Al₂O₃/0.032 Cu-TEPA/0.062TMAdaOH/0.062 TMAOH/12.3 H₂O.

The autoclave was heated to 140° C. and maintained at the temperaturefor 144 hours while stirring at 150 RPM. After cooling, the product wasrecovered by filtration, washed with deionized water, and dried in a110° C. convection oven. The as-synthesized product was examined by XRD,and it was found a Cu containing zeolite having chabazite framework hadbeen obtained (FIG. 2). The product was calcined in air at 600° C. for 5hrs to remove the residual organic. The occluded organic in the driedas-synthesized zeolite was removed by calcination in air at 600° C. for5 hours. The product had a SiO₂/Al₂O₃ ratio (SAR) of 21.4 and contained4.3 wt. % CuO (Table 1).

Example 3—Direct Synthesis of Cu-CHA

Sample 3 was prepared using the same protocol as described in Example 1except the molar composition of the final mixture was adjusted toprepare a CHA zeolite with a different SAR. The composition of the finalreaction mixture was 1.0 SiO₂/0.061 Al₂O₃/0.033 Cu-TEPA/0.067TMAdaOH/0.080TMAOH/12.9 H₂O.

The autoclave was heated to 160° C. and maintained at the temperaturefor 96 hours while stirring at 150 RPM. The product was examined by XRD,and it was found a Cu containing zeolite having chabazite framework hadbeen obtained. The product showed the X-ray diffraction pattern ofchabazite (FIGS. 3A and B). The product had a SiO₂/Al₂O₃ ratio (SAR) of16.6 and contained 4.1 wt. % CuO (Table 1).

Example 4—Direct Synthesis of Cu-CHA

Sample 4 was prepared using the same protocol as described in Example 1.The composition of the final reaction mixture was 1.0 SiO₂/0.042Al₂O₃/0.028 Cu-TEPA/0.062 TMAdaOH/0.062TMAOH/12.5 H₂O.

The autoclave was heated at 140° C. for 48 hours followed by 180° C. for24 hours while stirring at 150 RPM. The product was examined by XRD, andit was found a Cu containing zeolite having chabazite framework had beenobtained. The product showed the X-ray diffraction pattern of chabazite(FIGS. 3C and D). The product had a SiO₂/Al₂O₃ ratio (SAR) of 23.6 andcontained 3.6 wt. % CuO (Table 1).

Comparative Example 1

The method disclosed by Trukhan et al. in U.S. Pat. No. 8,715,618 B2(U.S. Pat. No. 9,272,272 B2) describes direct synthesis of Cu containingCHA prepared using a mixture of N,N,N-trimethyl-1-adamantyl ammonium(TMAdaOH) with trimethylbenzylammonium hydroxide (TMBA) or tetramethylammonium hydroxide (TMAOH) as the combined OSDAs, and Cu Nitrate orCu(NH₃)₄CO₃ as the Cu source. Example 10 from U.S. Pat. No. 8,715,618 B2is an example of the preparation of CHA zeolites from a gel thatcontains OSDAs TMAdaOH and TMAOH and Cu source Cu(NH₃)₄CO₃.

In this Example, the method was reproduced for comparison to the currentdisclosed methods. Aluminum triisopropylate, TMAdaOH, TMAOH,Cu(NH₃)₄CO₃, Ludox AS-40, deionized water and CHA seeds were mixed toform the reported gel composition of 36 SiO₂/2.7Alisoprop./2.6TMAdaOH/3.0TMAOH/1.02Cu amine/448H₂O, which was identical tothe reported gel composition of 36SiO₂/2.7Alisoprop./2.6TMAdaOH/3.0TMAOH/0.96Cu amine/448H₂O.

The gel was loaded into an autoclave (Parr Instruments) and heated to160° C. and maintained at the temperature for 48 hours while stirring at200 RPM. The product was recovered, dried, and calcined in air at 600°C. for 5 hrs. The product showed the XRD pattern of chabazite (FIG. 4).The CuO content and SAR of the material (3.1 wt. % CuO and 26.0 SAR)were very similar to those reported in Example 10 of U.S. Pat. No.8,715,618 B2 (3.0 wt. % CuO and 25.1 SAR). The SEM image (FIG. 10) alsoindicates a similar material to that reported in Example 10 of U.S. Pat.No. 8,715,618 B2.

The zeolites prepared using the method of Comparative Example 1 exhibitlower SCR activity than the current invention.

Comparative Example 2

The methods disclosed by Moliner Marin et al. in US 2016/0271596 A1describes the preparation of Cu containing CHA zeolites from a gel thatcontains Cu-TEPA with either N,N,N-trimethyl-1-adamantyl ammonium(TMAda+) cation or benzyl trimethylammonium cation (TMBA+) withoptionally one or more precursors including alkali cations and fluorideanions. All examples presented were prepared from gels that containsN,N,N-trimethyl-1-adamantyl ammonium (TMAda+) cations with the additionof either alkali cations or NH₄F.

Example 2 is an example of the preparation of Cu-CHA zeolites from a gelthat contains Cu-TEPA and N,N,N-trimethyl-1-adamantyl ammonium (TMAdaOH)with the addition of NaOH. The comparative sample was prepared using thesame protocol as described in Example 2. Copper (II) sulfate,tetraethylenepentamine (TEPA), N,N,N-trimethyl-1-adamantammoniumhydroxide, sodium hydroxide, aluminum hydroxide, and Ludox AS40 weremixed together to form a gel with the following molar composition: Thegel composition was SiO₂:0.033 Al₂O₃:0.049Cu(TEPA)²⁺:0.19 TMaDA:0.12NaOH:18.3 H₂O which was identical to the reported gel composition ofSiO₂:0.033 Al₂O₃:0.049Cu(TEPA)²⁺:0.19 TMaDA:0.12 NaOH:18.3 H₂O.

The final gel was loaded into Teflon-lined stainless steel autoclaves(Parr Instruments) and heated at 150° C. for 14 days under staticconditions. After filtering, washing, and drying, the product showed theXRD pattern of chabazite (FIG. 5).

The product was calcined in air at 550° C. for 6 hrs to remove theresidual organic. The SAR of the material (28.9 SAR) was similar to thatreported in Example 2 of US 2016/0271596 A1 (27.8 SAR). The 5.7 wt. %CuO content of the material was higher than the reported 4.0 wt. % CuObut is close to the initial 6.1 wt. % CuO content in the starting gel.The SEM image (FIG. 11) also indicates a similar material to thatreported in Example 2 of US 2016/0271596 A1.

The zeolites prepared using the method of Comparative Example 2 exhibitlower SCR activity than the current invention.

Comparative Example 3

The methods disclosed by Rivas-Cardona et al. in US 2015/0151286 A1 andUS 2015/0151287 A1 describes the preparation of Cu containing CHAzeolites from a gel that contains Cu-TEPA with a second OSDA TMAda (US2015/0151286 A1) or DMECHA (US 2015/0151287 A1) with optionally NaOH.

A comparative sample was prepared using the same protocol for thesynthesis of JMZ-4 as described in both [0032] and Example 1 presentedin 2015/0151286 A1. Since there is no specific gel composition availableprovided in the patent, we used a gel with molar compositionSiO₂:0.04Al₂O₃:0.30 TMAda:0.03 Cu-TEPA:18 H₂O falling in the claimedcomposition range. Aluminum source Al(OEt)₃ was combined with TMAda inwater and mixed for 30 minutes. Next, copper sulfate and TEPA were addedto the solution and the mixture was stirred for another 30 minutes.Finally, TEOS was added to the solution and mixed for 60 minutes.

The gel was loaded into an autoclave (Parr Instruments) and heated to160° C. for 5 days. After filtering, washing, and drying, the productshowed pure phase chabazite structure by XRD (FIG. 6). The product wascalcined in air at 560° C. for 8 hrs to remove the residual organic. TheCuO content and SAR of the material (2.9 wt. % CuO and 21.0 SAR) fall inthe 10-30 SAR range and 0.1-5 wt. % CuO range recited in US 2015/0151286A1.

The zeolites prepared using the method of Comparative Example 3 exhibitlower SCR activity than the current invention.

EXPERIMENTAL METHODS

This section summarizes methods used to identify and differentiateCu-CHA zeolites prepared using the disclosed synthetic method fromCu-CHA zeolites prepared using prior synthetic methods.

SCR Catalytic Tests:

The activities of the hydrothermally aged materials for NOx conversion,using NH3 as reductant, were tested with a flow-through type reactor.Powder zeolite samples were pressed and sieved to 35/70 mesh and loadedinto a quartz tube reactor. The gas composition for NH₃—SCR was 500 ppmNO, 500 ppm NH₃, 5 vol % O₂, 0.6% H₂O and balance N₂. The space velocitywas 50,000 h⁻¹. The reactor temperature was ramped between 150° C. and550° C. and NO conversion was determined with an MKS MultiGas infraredanalyzer at each temperature point.

One important feature of Cu-CHA zeolites prepared using the disclosedsynthetic method is that they exhibited both higher fresh and steamedSCR activity (at low temperature range 150° C., 175° C., 200° C.) thanCu-CHA zeolites prepared using prior synthetic methods (as shown inTables 2 and 3). For example, the SCR activity at 150° C. of the freshversions of the inventive examples is higher than 45%, such as higherthan 50%. It is well known that SCR performance of zeolite materials arerelated to structure differences. The Cu containing CHA zeolitesproduced by the disclosed method can be uniquely identified by methodsthat measure the detailed structure of the zeolites.

As shown below, XRD, FTIR spectroscopy, and FT-VIS spectroscopy can beused to differentiate the Cu CHA zeolites prepared from these disclosedmethods from CHA zeolites produced from prior synthetic methods.

X-Ray Diffraction (XRD) Patterns:

As shown in FIGS. 1-3, XRD patterns for the as-synthesized samplesprepared using the disclosed method exhibited a pronounced peaksplitting between 30-32° (FIGS. 1-3), which is not present or lessapparent in the products prepared from prior art (FIGS. 4-6). The peakareas of the [3,1,0] peak and the [3,−1,−1] peak were measured and thepeak area ratio of [3,1,0] vs. the whole peak doublet([3,1,0]+[3,−1,−1]) is further compared in Table 4. As an example, the[3,1,0] peak is located at about 31.2 degrees in FIG. 1B and the[3,−1,−1] peak is located at about 30.9 degrees in FIG. 1B. For thesamples prepared using the disclosed method, the peak area ratios aretypically high and are measured to be 0.19, 0.18, 0.26, and 0.21 for thesamples in Examples 1, 2, 3, and 4, respectively. For the Comparativeexamples, the ratios are below 0.12 and are all substantially lower thanthose of the inventive samples. These data indicate that CHA zeolitesamples prepared using the disclosed methods are different from thecomparative examples.

Scanning Electron Microscope (SEM) Images:

SEM provides a direct method to investigate the morphology differencebetween different zeolite materials. For the CHA zeolite samplesprepared using the disclosed methods (Examples 1, 2, 3 and 4), the SEMimages show that the samples consist of cubic crystals of a size of0.1-2 microns. The surfaces of the crystals contain small nanocrystals(FIGS. 7-9). The SEM images of the comparative examples (FIGS. 10-12)all indicate crystals different from samples prepared using thedisclosed methods.

FTIR ATR Spectroscopy Measurements:

FTIR spectra were obtained on calcined samples using a single bouncediamond attenuated total reflectance (ATR) accessory on a Nicoletspectrometer from Thermo Scientific. As shown in FIG. 13A, FTIR spectrafor the samples prepared using the disclosed method exhibited an intensepeak between 1030-1080 cm⁻¹, which is much higher than those of theproducts prepared from prior art (FIG. 13A). The peak near 1030-1080cm⁻¹ is a characteristic of the phonon vibration of coupled Si—O—Sioscillators in the crystal lattice, which was from the Si—O—Siasymmetric stretch. The FTIR spectra were also normalized based on thepeak near 805 cm⁻¹ (FIG. 13B), which was from Si—O—Si symmetric stretch.The ratio of the peak area of the peak between 900-1300 cm⁻¹ and thepeak between 765-845 cm⁻¹ was compared in Table 5. As shown in Table 5,the peak area ratios are measured to be 72, 85, 94, and 84 respectivelyfor Examples 1, 2, 3, and 4 prepared using the disclosed method. For theComparative examples, the ratios are all below 51 and are allsubstantially lower than those of the inventive samples. These dataindicate that CHA zeolite samples prepared using the disclosed methodsare different from the comparative examples.

FT-VIS Spectroscopy Measurements:

FT-VIS spectra were collected on calcined samples on a Bruker Vertex 80spectrometer under diffuse reflectance conditions utilizing a Harrickpraying mantis diffuse reflectance accessory. The background sample PTFEwas used as a reference material for background scans. FIG. 14 showsFT-VIS spectra for the samples normalized to 1 wt. % CuO content. FIG.14 also includes a Cu(OH)₂ powder as a reference. As shown in FIG. 14,the samples prepared using the disclosed method exhibited much lowerpeak areas in the 500-1100 nm range than those of the products preparedfrom prior art. The ratios of peak area of each sample relative to thereference Cu(OH)₂ peak area are compared in Table 6. The ratios arebelow 1.7 for Examples 1, 2, 3, and 4 prepared using the disclosedmethod and are higher than 2.8 for the Comparative examples.

Surface Area Measurements:

Surface area was determined in accordance with the BET(Brunauer-Emmett-Teller) nitrogen adsorption method. The generalprocedure and guidance of ASTM D4365-95 is followed in the applicationof the BET method to the materials according to the present disclosure.To ensure a consistent state of the sample to be measured, all samplesare pretreated. Suitable pretreatment involves heating the sample, suchas to a temperature of 400 to 500° C., for a time sufficient toeliminate free water, such as 3 to 5 hours. In one embodiment, thepretreatment comprises heating each sample to 500° C. for 4 hours.

Micropore Volume Measurements:

The assessment of micropore volume is particularly derived from the BETmeasurement techniques by an evaluation method called the t-plot method(or sometimes just termed the t-method) as described in the literature(Journal of Catalysis 1964, 3, 32).

TABLE 1 Analytical data for samples prepared from methods described inthis patent application compared to comparative examples. CuO Na₂O + MPVExample From SAR wt. % K₂O wt. % SA m²/g cc/g Inventive 1 22.2 3.7 0.08707 0.27 Inventive 2 21.4 4.3 0.11 733 0.27 Inventive 3 16.6 4.1 0.20760 0.28 Inventive 4 23.6 3.6 0.05 750 0.27 Comparative 1 U.S. Pat. No.8,715,618 26.0 3.1 0.08 681 0.25 Comparative 2 US 2016/0271596 28.9 5.70.64 727 0.27 Comparative 3 US 2015/0151286 21.0 2.9 0.04 671 0.22

TABLE 2 SCR activity (NO conversion at temperatures from 150-550° C.)over fresh samples prepared from method described in this patentapplication compared to samples prepared from prior reported methods.Temperature (° C.) 150 175 200 250 350 450 550 Example From NOconversion (%) Inventive 1 55.8 87.6 98.8 100 100 90.5 69.9 Inventive 278.1 99.3 100 100 100 94.9 74.0 Inventive 3 76.0 96.8 99.7 100 100 94.282.5 Inventive 4 68.6 96.9 99.7 100 100 88.4 82.0 Comparative 1 U.S.Pat. No. 8,715,618 39.5 70.3 93.9 99.9 99.4 87.8 75.2 Comparative 2 US2016/0271596 37.0 63.0 91.6 100 99.9 87.8 67.5 Comparative 3 US2015/0151286 37.8 64.1 87.2 99.5 99.6 87.9 76.8

TABLE 3 SCR activity (NO conversion at temperatures from 150-550° C.)over steamed samples prepared from method described in this patentapplication compared to samples prepared from prior reported methods.Steaming conditions: 750 C., 10% H₂O/air, 16 hours. Temperature (° C.)150 175 200 250 350 450 550 Example From NO conversion (%) Inventive 138.3 65.7 92.3 99.4 95.3 81.7 62.1 Inventive 2 41.4 71.4 93.7 99.7 96.182.8 62.4 Inventive 3 35.3 61.6 89.2 98.6 94.9 85.5 68.7 Inventive 440.3 79.1 98.7 100 100 90.9 75.9 Comparative 1 U.S. Pat. No. 8,715,61828.3 56.2 93.0 99.8 93.3 81.6 59.2 Comparative 2 US 2016/0271596 24.042.5 67.2 96.1 90.9 74.8 43.3 Comparative 3 US 2015/0151286 26.5 53.487.3 98.3 91.2 79.4 62.4

TABLE 4 The ratio of the [3, 1, 0] peak area and the total peak doubletarea ([3, 1, 0] + [3, −1, −1]). area of [3, 1, 0] peak/total area ([3,1, 0] Examples peak + [3, −1, −1] peak) Inventive 1 0.19 Inventive 20.18 Inventive 3 0.26 Inventive 4 0.21 Comparative 1 0.12 Comparative 20.12 Comparative 3 0.09

TABLE 5 The ratio of the peak area of the peak between 900-1300 cm⁻¹ andthe peak between 765-845 cm⁻¹ for Inventive examples and comparativeexamples. Peak area between 900-1300 cm⁻¹/peak Examples area between765-845 cm⁻¹ Inventive 1 72 Inventive 2 85 Inventive 3 94 Inventive 4 84Comparative 1 51 Comparative 2 41 Comparative 3 47

TABLE 6 The ratio of the peak area of Inventive examples and Comparativeexamples between 500-1100 nm relative to the peak area of the referenceCu(OH)₂ Examples Peak area/Reference Cu(OH)₂ peak area Inventive 1 1.1Inventive 2 1.1 Inventive 3 1.3 Inventive 4 1.7 Comparative 1 3.1Comparative 2 2.8 Comparative 3 4.5

Unless otherwise indicated, all numbers expressing quantities ofingredients, reaction conditions, and so forth used in the specificationand claims are to be understood as being modified in all instances bythe term “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that may vary depending upon thedesired properties sought to be obtained by the present disclosure.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with the true scope of theinvention being indicated by the following claims.

What is claimed is:
 1. A metal-containing chabazite zeolite, whereinsaid zeolite has an FTIR peak area ratio between the peak at 900-1300cm-1 and the peak at 765-845 cm-1 (˜805 cm-1 is Si—O—Si symmetricstretch) of at least
 55. 2. The zeolite of claim 1, wherein said zeolitehas a silica-to-alumina ratio (SAR) ranging from 5 to
 60. 3. The zeoliteof claim 1, wherein the metal is copper.
 4. The zeolite of claim 3,wherein the copper is present in an amount of at least 0.5 weightpercent of the total weight of the material.
 5. The zeolite of claim 4,wherein the copper comprises an amount ranging from 0.5 to 10 weightpercent of the total weight of the material.
 6. The zeolite of claim 1,wherein the metal is iron.
 7. The zeolite of claim 6, wherein the ironis present in an amount of at least 0.5 weight percent of the totalweight of the material.
 8. The zeolite of claim 7, wherein the ironcomprises an amount ranging from 0.5 to 10 weight percent of the totalweight of the material.
 9. The zeolite of claim 1, wherein the zeolitehas a total alkali oxide amount of less than 0.3 weight percent.
 10. Thezeolite of claim 1, wherein the peak area ratio between the FT-VIS peakbetween 500-1100 nm and the FT-VIS peak area of Cu(OH)2 between 500-1100nm is lower than 2.5.
 11. A method of selective catalytic reduction(SCR) of NOx in exhaust gas, said method comprising contacting exhaustgas with a zeolitic material comprising a copper containing CHA-typezeolite, wherein said material has an FTIR peak area ratio between thepeak at 900-1300 cm-1 and the peak at 765-845 cm-1 (˜805 cm-1 is Si—O—Sisymmetric stretch) of at least
 55. 12. The method of claim 11, whereinsaid contacting step is performed in the presence of ammonia or urea.13. A method of making a microporous crystalline material from reactionmixtures that are essentially void of alkali metal cations and compriseorganic structure directing agents (OSDA) selected from the groupconsisting of (1) metal-polyamine as the first OSDA, (2)N,N,N-trimethyl-1-adamantyl ammonium (TMAda+), ortrimethylbenzylammonium (TMBA+) or N,N,N-dimethylethylcyclohexylammonium(DMECHA+) organic or mixtures thereof as the second OSDA, and (3) TMA+or TEA+ or mixtures thereof as the third OSDA, the method comprising: a)mixing sources of alumina, silica, water, a first OSDA, a second OSDAand optionally a third OSDA and optionally a seed material to form agel; b) heating the gel in a vessel at a temperature ranging from 80° C.to 250° C. to form a crystalline chabazite product that exhibits an XRDpeak area ratio between the [3,1,0] peak and the peak doublet (sum of[3,−1,−1] peak and [3,1,0] peak) of at least 0.15; and c) calcining theproduct to produce an aluminosilicate zeolite having a CHA structure,and a silica-to-alumina ratio (SAR) ranging from 5 to
 60. 14. The methodof claim 13, wherein the reaction mixture has a molar composition of 1SiO2:m Al2O3:n metal-polyamine:x TMAdaOH:y TMAOH:z H2O, wherem=0.016-0.2, n=0.01-0.12, x=0.01-0.50, y=0.01-0.50, z=1-50.
 15. Themethod of claim 13, wherein the metals used for forming metal-polyamineof the first OSDA are selected from Cu, Fe, Mn, Co, Ni, Pd, Pt and Zn.16. The method of claim 13, wherein the polyamine of the first OSDA isselected from diethylenetriamine, triethylenetetramine,tetraethylenepentamine, pentaethylenehexamine, N, N-(2-hydroxyethyl)ethylenediamine, N,N-bis(2-aminoethyl)-1,3-propanediamine,1,2-bis(3-aminopropylamino), 1,4,8,11-tetraazacyclotetradecane,1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, and combinationsthereof.
 17. The method of claim 16, wherein the polyamine istetraethylenepentamine (TEPA).
 18. The method of claim 13, wherein thesource of alumina is chosen from aluminum trihydroxide, alumina,pseudoboehmite alumina, silica-alumina and Al isopropoxide.
 19. Themethod of claim 13, wherein the source of silica is chosen from silicasol, silica gel, precipitated silica, silica-alumina and fumed silica.